Hydraulic systems with increased speed of response



March 17, 1970 A. 1 STROM 3,500,723

HYDRAULIC SYSTEMS WITH INCREASED SPEED OF RESPOESE Original Filed Feb. 16, 1965 2Sheets-S heet 1 ACCUMULATOR OIL AUXILIARY OIL FIG-I.

INVENTOR Albert P STrom BY ATTORNEY March 17, 1970 A. P. STROM 3,500,723

HYDRAULIC SYSTEMS WITH INCREASED SPEED OF RESPONSE- Original Filed Feb. 16, 1965 2 Sheets-Sheet 2 HYDRAULIC ACCUMULATOR .III

United States Patent 3,500,723 HYDRAULIC SYSTEMS WITH INCREASED SPEED OF RESPONSE Albert P. Strom, Forest Hills, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Original application Feb. 16, 1965, Ser. No. 432,983, now Patent No. 3,345,487, dated Oct. 3, 1967. Divided and this application July 7, 1967, Ser. No. 651,851

Int. Cl. Fb 17/02, 7/00; F16j 9/00 US. Cl. 91-460 4 Claims ABSTRACT OF THE DISCLOSURE CROSS REFERENCES TO RELATED APPLICATIONS This application is a division of United States patent application filed Feb. 16, 1965, Ser. No. 432,983, entitled Hydraulically Operated Circuit Breaker, now US. Patent 3,345,487, issued Oct. 3, 1967, and the benefit of said filing date is claimed for this application.

BACKGROUND OF THE INVENTION For ordinary purposes the speed of response in a hydraulic system can be considered as instantaneous. By this is meant when pressure is applied at one point of a hydraulic line or system, equal pressure is instantaneously present at all other points in the line.

Actually, there is a slight delay between the instant that pressure is applied to one end of a hydraulic line and when it is available at the other end. The pressure wave travels from one end to the other at the velocity of sound in the oil. The sound velocity in oil is slow as compared to most solids. This would appear to put the use of hydraulic means for the tripping of large high voltage circuit breakers at a slight disadvantage over direct opera tion of the trip by means of solid mechanical connections. However, the need to use massive moving mechanical SUMMARY OF THE INVENTION In accordance with one embodiment of the invention, a loosely fitting member, which may be either solid or hollow, is disposed inside a hydraulic line which, for example, interconnects a pilot valve and a control valve. According to another embodiment of the invention, a solid rod of insulating material is utilized having hydraulic operating cylinders at each end of the rod of solid material. Thus a pressure is applied to the cylinder at one end of the rod and this pressure is transmitted through the solid rod to the other cylinder at the Opposite end of the rod.

An object of the present invention is to increase the speed of response of a hydraulic system.

A more specific object of the present invention is to increase the speed of response of a hydraulic system by parts joints, levers, hinges, etc. in mechanical systems generally more than offsets the advantage gained by faster sound transmission. Also, speed of sound transmission becomes important only in very high speed operation where the saving of a fraction of a cycle in interrupting time is essential. In such high speed breakers, it would, of course,

be desirable when using hydraulic operation to eliminate this difference of speed of response due to slower velocity of sound in oil, thereby retaining the advantages of direct hydraulic operation without moving mechanical parts.

The speed of response of a hydraulic system can be increased to practically that of solid materials by filling the hydraulic line with one or more loosely fitting cylinders of solid material having a high speed of response. Another method which is proposed to increase the speed of response of a hydraulic system is to utilize a solid rod of insulating material with hydraulic operating cylinders at each end of the rod of solid material.

providing a loosely fitting member, which may be either solid or hollow, inside a hydraulic line.

Another object of the present invention is to increase the speed of response of a hydraulic system by utilizing a solid rod of insulating material, or for certain applications metallic material having hydraulic operating cylinders at each end of the rod of solid material.

Still a further object of the present invention is to increase the speed of response of a circuit interrupter having hydraulic operation.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF PREFERRED EMBODIMENTS Referring to the drawings, particularly to FIG. 1, the circuit breaker structure shown therein comprises a mechanism housing 11 having a pair of interrupting units 12 extending from opposite sides thereof, insulating members 13 for supporting the housing 11 which is maintained at a relatively high potential, and control apparatus 14 which may be at ground potential and enclosed in a suitable housing (not shown). Each interrupting unit 12 includes an arc-extinguishing structure 15 enclosed within a porcelain weatherproof hollow casing 16 only a portion of which is shown. The casing 16 extends laterally from the housing 11 and is attached to the side of the housing by means of a flanged rim 17 which may be cemented to the porcelain casing 16 and attached to the housing 11 by suitable bolts. The circuit breaker may be generally of the type fully described in Patent No. 3,075,060, is sued Jan. 22, 1963, to A. P. Strorn and assigned to the Westinghouse Electric Corporation.

Each arc-extinguishing structure 15 includes a relatively stationary, generally tubular contact member 21, only a portion of which is shown, and a movable contact assembly 22 comprising a plurality of contact fingers 23 and an arcing contact member 24. The contact fingers 23 and the arcing member 24 are removably attached to a sliding valve member 25 disposed inside a casing 26 supported within the mechanism housing 11. The valve member 25 and the movable contact assembly 22 are actuated in a manner which will be fully described here inafter.

The contact fingers 23 slidably engage the tubular contact member 21 which may be of the type fully described in a copending application Ser. No. 61,284, now Patent No. 3,154,658, filed Oct. 7, 1960, by R. G. Colclaser and R. N. Yeckley and assigned to the Westinghouse Electric Corporation. A generally cup-shaped orifice member 27 is also removably attached to the sliding valve member 25. The orifice 27 has an opening 28 therein through which the contact member 21 extends, a relatively tight fit being maintained between the contact member 21 and the orifice 27. The orifice 27 is preferably composed of polytetrafluoroethylene which is sold under the trade name Teflon.

The mechanism housing 11, the interrupting units 12 and a vertically disposed porcelain casing 29 are filled with an interrupting gas, for example sulfur hexafluoride (SP which is maintained at a relatively low pressure, for example 60 p.s.i. In order to supply high pressure gas during the interrupting operation, a single puffer mechanism 31 is provided to supply gas to the two interruping units 12 which are serially connected in an electric circuit in the manner described in the aforesaid patent.

The puffer mechanism 31 comprises a piston 32 disposed inside a cylindrical portion 33 of a member 34 mounted within the mechanism housing 11. The piston 32 is actuated by a hydraulic operator 35, the operation of which is controlled by a hydraulic control valve 36 which, in turn, is controlled by a pilot valve 37 in a manner fully described hereinafter.

The sliding valve and movable contact assembly of each arc-extinguishing structure are actuated by a hydraulic operator 38 each one of which comprises a piston 39 disposed within a cylinder 41 mounted in the mechanism housing 11. A piston rod 40 is attached to the valve 25. The operators 38 are both controlled by a single hydraulic control valve 42 which, in turn, is controlled by a pilot valve 43.

A hydraulic accumulator 44 supplies oil at a high pressure to the hydraulic operators and the control valve, and a sump 45 receives discharged oil from the operators and the valves. An auxiliary accumulator 46 may be provided. The accumulators may be of a type well known in the art, each comprising a chamber which is separated into two compartments by a movable piston 47. One compartment contains a compressible gas, such as nitrogen, at a relatively high pressure for example 2000 p.s.i. and the other compartment contains oil. The oil pressure in the accumulator is maintained by a compressor 48 driven by a motor 49. The compressor 48 withdraws oil from the sump 45 through a hydraulic line 51 and returns it to the accumulators through a check valve 52 and a hydraulic line 53.

The hydraulic operators 35 and 38, the control valves 36 and 42, and the pilot valves 37 and 43 are similar to those described in the aforesaid patent and their manner of operations is in general, similar to that described in the patent. However, in order to increase the interrupting ability of the circuit breaker, the contact operation is separate from the puffer operation and provision is made for opening the contacts at any desired point of the puffer motion. Furthermore, the flow of compressed gas from the puffer into the interrupting units is delayed until high pressure has been built up in the puffer, thereby preventing the loss of any of the puffer gas prior to the opening of the contact members and the drawing of an are between the contact members.

When the contact members begin to move, ports 55 are opened by the sliding valves 25, thereby permitting high pressure gas from the puffer 31 to flow into the arcextinguishing structures 15 to interrupt the arcs in the manner described in the aforesaid copending application. Since the puffer has traveled a suflicient distance to build up a high pressure before the ports and the contact members are opened, high interrupting ability is instantly available. The gas from the interrupting units is discharged into the mechanism housing 11 through openings 56.

As explained hereinbefore, the hydraulic operators are similar to those described in the aforesaid patent. The operators are of the balanced pressure type. Thus, when equal fluid pressure is applied to opposite sides of the piston 57 of the operator 35 the puffer piston 32 is retained in its uppermost position because of a difference in cross sectional areas of piston rods 58 and 59. Likewise, when equal fluid pressure is maintained on opposite sides of the piston 39 in each operator 38 the contact members of the interrupters are retained in the closed position. The puffer piston 32 is actuated to its lowermost position and the contact members are opened by reducing the fluid pressure on one side of the pistons in the operators 35 and 38 by means of the control valve 36 and 42, respectively.

The control valves 36 and 42 are similar to those described in the aforesaid patent. Thus, by way of example, the valve 42 comprises a piston 61 which is attached to a sleeve valve 62 by means of a spider 63. The valve 62 controls the flow of high pressure oil downwardly through passages 64 in a valve casing 65. When the valve is in the position shown, oil is permitted to flow across the top 66 of the valve and out through ports 67 and through a hydraulic line 68 and thence into one end of the cylinder 41 of the operators 38 causing operators 38 to move toward the closed contact position. The other end of each cylinder is connected to the accumulator 44 through a hydraulic line 69.

When a projecting end 71 of a spindle 72 in the pilot valve 43 is engaged by a cam 73 carried by the piston rod 59 of the puffer operator 35, the spindle 72 is actuated to permit high pressure oil from the accumulator line 69 to flow through a port 74 into a line 75 to apply pressure to the lower end of the piston 61 in the control valve 42. This pressure raises the piston 61 against the force of a spring 76, thereby closing the opening 66 and permitting oil to be discharged from the operators 38 through ports 67 and passageways 77 into a chamber 79 which is connected to the sump 45 through the sump line 51. In this manner, the operators 38 actuate the slide valves 25 to open the ports 55 and also to open the contact members of the arc-extinguishing structures.

The cam 73 may be adjusted on the piston rod 59 to operate the pilot valve 43 at any desired point on the travel of the puffer piston 32, thereby determining the time at which the contract members are opened with reference to the travel of the puffer piston. As previously explained, the compressed gas from the puffer cannot escape through passageways 80 and the ports 55 into the interrupting chamber until the side valves 25 are opened along with the contact members of the arc-extinguishing structures.

The pilot valve 37 is shown in the tripped position. As shown, a solenoid 81 has been energized to actuate a latch 82 against the tension of a spring 83, thereby releasing the latch from a shoulder 84 on a valve spindle 85. Thus, high pressure fluid is permitted to flow from the high pressure line 53 through a port 86 into a line 87 and thence to the control valve 36 which is operated in the same manner as the valve 42 to release the fluid pressure from the lower side of the piston 57 in the puffer operator 35, thereby causing the puffer piston 32 to be driven downwardly to compress gas in the cylinder 33. At a predetermined point in the downward movement of the piston 32, the cam 73 operates the pilot valve 43 to open the contact members of the interrupters in the manner previously described.

When it is desired to close the contact members of the circuit breaker, a solenoid 91 is energized to move the spindle to the left against the force of a spring 92, thereby permitting fluid to be discharged from the control valve 36 through the pilot valve 37 into the sump line 51. The control valve 36 is operated to permit high pressure fluid to enter the operator 35 through the line 88, thereby driving the puffer piston 32 to its uppermost position. When the cam 73 is disengaged from the projection 71 of the pilot valve 43, the spindle 72 is actuated by a spring 93 to the position in which oil is released from the control valve 42, thereby causing this valve to admit high pressure oil to the operators 38 to close the contact members of the interrupters.

As previously explained, the sump chamber 45 is located within the mechanism housing 11, thereby permitting it to operate at the pressure of the SP gas within the mechanism housing. In order to prevent the oil within the sump chamber from being exposed to the gas, so that no gas is absorbed in the hydraulic oil to cause foaming, the sump chamber is covered with a neoprene diaphragm 95.

Locating the sump chamber 45 within the mechanism housing 11 eliminates the necessity of providing a large sump return line from the mechanism housing to the sump chamber. Thus, only three insulating lines are required between the apparatus which is at ground potential and the apparatus which is at the high operating potential of the circuit breaker. Each one of these three lines may be relatively small in diameter, thereby permitting the porcelain insulating casing 29 which encloses the three lines to be relatively small in diameter which reduces its cost.

Another advantage of the present structure is that the mechanism housing 11 serves as the storage for the SP gas. The porcelain arc chambers 16 are reduced in diameter, hence the cost is reduced, due to the discharge of the interrupting gas being in communication with the central gas storage chamber. As previously explained, the interrupting ability of the interrupters is increased by making the operation of the contact members separate from the operation of the putter and so timing the opening of the contact members and the valves which control the admission of the interrupting gas into the interrupters that only high pressure gas is admitted into the interrupters to obtain maximum performance of the interrupting gas.

For extremely high current interruption, parallel resistors may be desirable. These may be of the type described in the aforesaid patent and may be mounted in additional tubular porcelain chambers paralleling the main interrupting chambers and similar to, but smaller than, the main porcelain. Interrupting contacts would also be located in these resistor tubes of similar structure and contact separation as those shown for the main interrupters, but of smaller size. The operation of these contact members would also be initiated by the cam on the puffer operator piston rod extension, operating on aseparate pilot valve and control valve functioning in the man ner of the valves herein described.

For ordinary purposes the speed of response in a hydraulic system can be considered as instantaneous. By this is meant when pressure is applied at one point of a hydraulic line or system, equal pressure is instantaneously present at all other points in the line.

Actually, there is a slight delay between the instant that pressure is applied to one end of a hydraulic line and when it is available at the other end. The pressure wave travels from one end to the other at the velocity of sound in the oil. The sound velocity in oil is slow as compared to most solids. This would appear to put the use of hydraulic means for the tripping of large high voltage circuit breakers at a slight disadvantage over direct operation of the trip by means of solid mechanical connections. However, the need to use massive moving mechanical parts joints, levers, hinges, etc. in mechanical systems generally more than ofisets the advantage gained by faster sound transmission. Also, speed of sound transmission becomes important only in very high speed operation where the saving of a fraction of a cycle in interrupting time is essential. In such high speed breakers, it would, of course, be desirable when using hydraulic operation to eliminate this difierence of speed response due to slower velocity of sound in oil, thereby retaining the advantages of direct hydraulic operation without moving mechanical parts.

The speed of response of a hydraulic system can be increased to practically that of solid materials by filling the hydraulic line with one or more loosely fitting cylinders of solid material having a high speed of response. Glass, for example, is such a material. Even wood of some types or Micarta may be utilized where the hydraulic line must be of insulating material. Where insulation is not necessary, a steel or other metallic cylinder may be utilized, thereby providing extremely high rates of response.

It is not necessary to fill the entire length of hydraulic line with these solid cylinders since if most of the line is filled the loss of time of response due to the oil will be small. Thus, bends or curves in the hydraulic line need not be filled with a solid material.

Such a system is particularly applicable to the tripping of high speed, high voltage circuit breakers where the operating valve is located at high potential, at a considerable distance above ground. FIG. 2 shows how a system may be applied to a circuit breaker of the type described hereinbefore. Calculations show that approximately two milliseconds can be saved by this system over a straight hydraulic system for each ten foot length of hydraulic As shown in FIG. 2, a loosely fitting member 96, which may be either solid or hollow, is disposed inside a hydraulic line 87' which interconnects a pilot valve 37' and a control valve 36' of the type hereinbefore described. The member 96 may be composed of a suitable solid material, such as glass or steel as previously mentioned. A

spring rest 97 for the member 96 may be provided at the lower end of the line 87'. A hydraulic shock absorber comprising a spring 98 disposed inside a housing 99 may be provided at the upper end of the line 87'.

When high pressure oil is admitted to the lower end of the line 87' through the pilot valve 37, the pressure wave travels through the solid material 96 more rapidly than it would through a column of oil, thereby increasing the speed of response of the control valve 36' and the hydraulic operator 35. This, in turn, increases the speed of response of a member or members actuated by the hydraulic operator.

Another method for high speed response in a hydraulic system is to utilize a solid rod of insulating material, such as glass, from ground potential to high potential, with hydraulic operating cylinders at each end of the rod of solid material. Thus a pressure is applied to the cylinder at ground potential, which may be considered the control cylinder. This pressure is transmitted through the solid rod to the upper cylinder which is at high potential and may be considered the controlled cylinder. A piston in the upper cylinder is actuated to open the valve or trip a latch.

As shown in FIG. 3, a piston 101 may be disposed in a cylinder 102 and biased to its uppermost position by a spring 103. The piston 101 is connected to a piston 104 by means of a rod 105 of solid material. The piston 104 is disposed inside a cylinder 106 containing oil. The cyl inder 106 may be connected to a main operating valve or trip release by means of a line 107. The piston 104 has an opening 108 therethrough connecting to an oil reservoir above the piston to insure pressure of oil under piston 104. The opening 108 is closed by a pin valve 109 when the piston moves downwardly. Thus, when high pressure oil is admitted to the upper side of the piston 101 through an opening 111, which may be connected to a suitable pilot valve or other control means, the pistons 101 and 104 are both moved downwardly simultaneously. The piston 104 forces oil through the line 107 to the main operating valve or trip release. The solid operating rod 105 has a higher speed of response than a column of oil of the same length, yet retains the advantages of hydraulie operation of the trip or other mechanism at high potential by means of a hydraulic operator at ground potential.

It is apparent that the speed of response of a hydraulic system may be increased by utilizing the structure hereinbefore described. The interrupting ability of a circuit breaker may be increased by utilizing the hydraulic operating system herein described. However, the applications are not limited to circuit breaker operations, but may be applied in any hydraulic system where it is desirable to increase the speed of response.

Since numerous changes may be made in the apparatus herein described and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all subject matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. In a circuit breaker, in combination, a hydraulic operator for actuating members of the breaker, a hydraulically operated control valve for controlling the hydraulic operator, a pilot valve disposed remotely from the control valve, a hydraulic line interconnecting the pilot valve and the control valve, and an elongated rod-shaped member movably disposed in said hydraulic line and substantially filling up the entire length of the hydraulic line.

2. The combination of claim 1, wherein the elongated rod-shaped member is hollow.

3. In a hydraulic system, in combination, a hydraulic operator and a control valve operatively associated with said operator, a pilot valve, a hydraulic line of electrically insulating material interconnecting the pilot valve and the control valve, and an elongated rod-shaped member of electrically insulating material movably disposed in said hydraulic line and substantially filling up the entire length of the hydraulic line.

4. In a hydraulic system, in combination, an elongated rod-shaped member of appreciable length having hydraulic pistons attached to the opposite ends thereof, a pair of spaced hydraulic operating cylinders within which the hydraulic pistons move, and one piston having an opening (108) therethrough for oil filling which is closed on the working stroke by a stationary pin moving therein.

References Cited UNITED STATES PATENTS 599,807 3/1898 Short 92-130 X 1,000,784 8/1911 Cumming 92-138 X 2,597,404 5/1952 Teske -545 X 2,777,427 1/ 1957 Nichols 92248 X 1,211,680 1/1917 Constantinesco 60-545 2,648,949 8/1953 Taylor 60-1 2,867,088 1/1959 Kux 60-545 3,075,060 1/1963 Strorn 200-148 CARROLL B. DORITY, JR., Primary Examiner US. Cl. X.R. 

